Some Hamilton residents were on alert on Wednesday night as Waikato River levels rise.
The river is expected to rise to about 15.5 metres, but houses will be at risk if it goes to 16 metres.
On Thursday morning, the level was at 15.15 - 15.20 metres.
Civil Defence put 30 homes on Ann Street and Awatere Avenue on alert. The Waikato Stadium is on standby in case there's an evacuation.
The levels are rising because water is being released to relieve pressure on Lake Karapiro.
The release began at 6pm: river levels in Hamilton began rising from 11pm.